In December 2011, one of New York’s top judicial officials demanded Family Courts remain open to the public — but in the past month, Manhattan judges have begun posting “Do not enter” signs on their courtroom doors.

At least five judges and referees out of 18 have affixed signs to their doors with a red stop sign reading, “Court Personnel Only.”

Open courtrooms serve as a check on government, and Edwina Richardson-Mendelson, the administrative judge of city Family Courts, was so troubled by a pattern of court officers flouting the open-courts rule that she ordered a review in 2011.

It resulted in a mandate “to ensure public access to Family Court proceedings.”

An attorney alerted The Post when he noticed a sign outside Judge Gloria Sosa-Lintner’s courtroom at 60 Lafayette St. that warns: “Do not knock on the door. Do not enter the courtroom. Wait for a court officer to check in.”

Peter Campbell, of the White Plains firm Tilem and Campbell, worries that Family Court proceedings can happen in a vacuum because the system does not have juries.

“We need that buffer for the public to come in and oversee proceedings,” Campbell insisted.

“Family Court is the perfect example of why we need courtrooms open to the public.”

A senior court clerk told The Post the signs started going up about a month ago at the request of individual judges.

Judges get copies of the signs from the chief clerk’s office, he explained, adding that there was no policy regulating their posting.

The signs are meant, “to avoid disruptions” while trial is in session, he said, although they remain affixed even when court is not in session.

“The judges just want to know who’s in their courtroom,” a court officer explained, noting the sensitive nature of the court, which handles cases of domestic violence, foster care and child neglect.

He added, “We won’t stop anyone from entering,” although the warning signs leave the opposite impression.